Decelerometer apparatus



C. M. HINS DECELEROMETER APPARATUS Filed Oct.' 29, 2.942

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INVENToR Claude Mlme BY Patented Jan. 22, 1946 DECELEROMETER APPARATUSClaude M. Hines, Pittsburgh, Pa., assignor to The Westinghouse Air BrakeCompany, Wilmer-ding, Pa., a corporation of Pennsylvania ApplicationOctober 29, 1942, Serial No. 463,749

Claims. (Cl. 20G-80) This invention relates to apparatus, designated forconvenience herein as decelerometer apparatus, effective to detect orregister variations in the rate of rotational acceleration ordeceleration of a rotary element and has particular relation todecelerometer apparatus of the rotary inertia type.

Heretofore known decelerometer apparatus of the rotary inertia typecomprises essentially a ilywheel that is driven through a resilientconnection from a driving shaft and that has rotational movement withrespect to the driving shaft in proportion to the rate of accelerationor deceleration of the driving shaft. Such decelerometer apparatus hasbeen employed for detecting the rate of rotative acceleration ordeceleration of a railway car wheel or wheel and axle unit for a desiredindicating or control purpose. For example, such decelerometer apparatushas been employed to detect the slipping condition of vehicle wheels onthe basis of the abnormal rate of rotative deceleration or accelerationof the wheels during the slipping condition thereof and to so controlthe brakes associated with the slipping wheels, or the propulsion meansapplying propulsion torque to the wheels, in a manner to .preventsliding of the wheels and to cause cessation of the slipping condition.

The terms "slipping" and sliding" as applied herein to vehicle wheelsare not synonymous. The term slipping refers to rotation of a vehiclewheel at speeds diil'erent from that corresponding to vehicle speed at agiven instant; whereas, the term "siiding refers solely to the locked ornonrotative condition of a vehicle wheel.

My present invention is a novel form of decelerometer apparatus suitedparticularly for detecting the slipping condition of railway car wheels.It comprises essentially (l) a ily-wheel element driven by rotation of adriving shaft, through an eddy current clutch, at a speed having asubstantially constant normal percentage slip relation to the drivingshaft; (2) two centrifuge devices, one rotatable at all times accordingto the rotational speed of the driving shaft, and the other rotatable atall times according to the rotational speed of the ily-wheel element;and (3) two elements respectively responsive to the instantaneousrotational speeds of the two centrifugedevices and cooperating in amanner to effect operation o! a switch device only when the respectiverotational speeds of the two centrifuge devices vary substantially fromtheir normal relation corresponding to the normal percentage slip of theily-wheel with respect to the speed of the driving shaft. The percentageslip of the ily-wheel with respect to the speed of the driving shaft inturn varies with the rate of acceleration or deceleration of the drivingshaft.

My decelerometer apparatus is particularly suited for the control ofvehicle lwheel brakes in that it not only initiates the release of thebrakes substantially at the instant the slipping condition of thevehicle wheel occurs, but also inherently operates to cause a continuingreduction in the degree of application of the brakes associated with thewheel as long as the wheel is in a slipping condition. The manner inwhich my improved decelerometer apparatus effects this result will bepointed out in detail hereinafter but it is suilicient to state for themoment that my improved decelerometer apparatus differs from heretoforeknown rotary inertia type decelerometer apparatus in that it obviatesthe need for additional apparatus, required in connection withheretofore known rotary inertia type decelerometer apparatus, forcausing a continuing reduction in the degree of application of thebrakes after the decelerometer apparatus initiates the reduction in thedegree of application of the brakes. v

It is accordingly an object of my invention to provide noveldecelerometer apparatus of the rotary inertia type for detectingvariations in the rate of acceleration or deceleration of a rotaryelement.

More specifically, it is-an object of my invention to provide noveldecelerometer apparatus of the rotary inertia type which is not onlyoperatively responsive to the slipping condition of a vehicle wheel butwhich is inherently maintained in its operated condition notwithstandingchanges in the rate of deceleration or acceleration of the slippingwheels occurring in response to the initial operation of the apparatus.

The above objects, and other objects of my invention which will be madeapparent hereinafter, are attained by means of apparatus subsequently tobe described and shown in the accompanying drawing wherein Fig. 1 is avertical sectional view, illustratively showing my novel decelerometerapparatus as employed in connection with a railway car wheel and axleunit,

Fig. 2 is a fragmental sectional view, taken on the line 2-2 of Fig. l,showing further details of construction, and

Fig. 3 is a fragmental diagrammatic view showing the manner in which mydecelerometer apparatus may be utilized to control the fluid presvehiclewheels.

Description Referring to the drawing, my novel decelerometer apparatusis shown in connection with the axle II of a railway car wheel and axleunit, the axle being journaled at one end as by miler bearings I2 in ajournal casing I3. The decelerometer apparatus comprises a suitabletubular or cylindrical'casing I4 which is secured by a clamping ring Ilto an adapter ring It that is, in turn, secured to the end of thejournal casing Il in place of the usual end cover. Casing I4 has aradially extending flange Il, of V-shape in cross section, that isresiliently clamped between the clamping ring Il and the adapter ring I6with an intervening cushioning ring Ita of rubber or other similarmaterial, for absorbing shock and vibration which would otherwise betransmitted from the axle I I.

Two centrifuge devices I1 and Il, respectively, are rotatively mountedwithin the casing I4.

'I'he centrifuge device I1 comprises a non-magnetic disk portion I Qhaving an integral hub portion 2| rotatively mounted, as by a rollerbearing race 22, in the central opening of an end flange or cover 23attached as by screws 24 to the casing I4. Screwed on the end of the hub2| is a flange member 25 having a plurality of radially extending slots26, shown illustratively as two in number, in which the smooth outerends of stud bolts 21 screwed into the end of the axle II, are receivedto provide a driving connection or coupling between the centrifugedevice I1 and the axle I I.

The disk I 9 has an externally threaded annular projection 2l on which acylindrical member 2l is screwed in coaxial relation to the Cylindricalmember 29 is of magnetic material and is formed to provide twodiametrically opposite radially extending salient pole-pieces 3| and 32.The member 29 is permanently magnetized so as to cause the pole-piecesll and 32 to be of opposite magnetic polarity.

A ball bearing race I4, retained in the casing I4, provides a supportfor member." and consequently the end of the centrifuge device I1.

The disk I9 is provided with oppositely extending radial slots 38, ineach of which a lever 3l carrying a weight 39 at the end thereof, ispivotally mounted as on a pin 31.

The hub 2| of the centrifuge device I1 has a central bore 4I. Extendingaxially through the bore 4I is a switch operating rod 42, one end ofwhich is slidably supported in a recess 43 in the flange member 25 incoaxial relation to the axis of rotation of the axle II. The rod 42 hasa collar 44 fixed thereon, and a coil spring 4I is interposed in thebore 4I between the collar 44 and the flange member 25 and yieldinglyurges the rod 42 in the left-hand direction.

The inner ends of the levers Il extend into close proximity to the rod42 and exert a force on the collar 44 in opposition to the force ofspring 4I due to the centrifugal force acting on the weights 39 when thecentrifuge device I1 is rotated. A suitable thrust bearing 41 isinterposed between the ends of the levers 38 and the collar 44 toeliminate friction 'between the levers andthe collar due to rotation ofthe disk II with respect to rod 42.

The rod 42 is accordingly shifted axially to different positions by thecentrifugal force acting axle II.

on the weights I of the centrifuge device Il in axlecorresponIl dencewith the speed of rotation of the The centrifuge device Il inductor ringand ily-wheel 4s, hereafter referred to simply as the fly-wheel, whichis rotatably supported in coaxial relation to the axle II on acylindrical member I2 that is attached, as by a screw-threadedconnection, to a central boss IJ on the disk Il of centrifuge device I1.Two ball races 4I, one at each end of the iiy-wheel 4l, may be providedfor rotatably mounting the ily-wheel on the member I2.

The ily-wheel 4I is of metal having electric current conductingproperties, such as copper, brass or alloys thereof, and thus acts as anin ductor ring in association with the pole-pieces II and 32 to form aneddy current type of clutch and brake between the disk I! and thefly-wheel 4 The outer end of the fly-wheel 4l has two yokes 54, in eachof which a lever 5I that carries a weight 51 at the outer end thereof ispivotally supported, as on a pin 5i. The inner ends of the two levers 56act through a suitable thrust bearing race I! on a shoulder 6I formed ona sleeve member 62.

'I'he sleeve member 62 is slidably supported at one end in a smooth boreIl of the cylindrical member 52. A coil spring tl retained in a bore 44in the sleeve member I2 engages the boss Il of the disk Il at one endand a thrust bearing race 61 contained in the bore I4 at its other end,to exert a force on the sleeve member 82 urging it in the left-handdirection.

Sleeve member 62 has a portion of reduced diameter at the left-hand endthereof which is slidably supported in a suitable journal bearing or hub64 formed in or attached to an end cover 6l that is, in turn, attachedas by a plurality of screws 10 to the outer end of the casing I4.

A key 12 can'ied by the sleeve member 62 engages in a slot 12 in the hubil to permit axial sliding movement of the sleeve member i2 with respectto 'the hub while preventing rotation of the sleeve. It will be seenthat the thrust bearcomprises a combined ing race 5l permits cooperationof the levers 50 of the centrifuge device I l with the sleeve member 62so as to minimize friction due to the rotation of the arms 56 withrespect to the sleeve. In a similar manner, the thrust bearing race G1permits the spring i5 to exert a force on the nonrotative sleeve 62while the spring rotates with the disk I9 of the centrifuge device I1.

It will be accordingly understood that the centrifugal force acting onthe weights 51 is effective to urge the sleeve member 62 in therighthand direction in opposition to the force of the spring IS, theaxial pomtion assumed by the sleeve member l2 correspondingsubstantially to the actual speed of rotation of the, centrifuge deviceIl.

'I'he switch operating rod 42 extends through and projects out of acentral bore 1B in the portion of the sleeve member 62 of reduceddiameter and is slidably guided therein.

Secured on the end of the sleeve member 62 within a chamber 1l formed bya central tubular extension of the end cover l! and closed by aremovable cover plate l., is a base 11 of suitable insulating material.Two flexible contact fingers 1land1laresecuredtothebase11inaxiallyspaced relation on one side of the rod 42. A flexiblecontactilngerllissecuredtothebase l1 and extends diametrically into the space betweenthe two contact fingers 18 and 1l for cooperative alternative engagementtherewith in the manner presently to be explained. f n

The contact finger 8| is ,of such character and location as to have aninherent bias in the direction of the contact finger 18. The outer ortip end f the rod 42 is of insulating material and engages the contactfinger 8| to shift the contact finger 8| to a normal position midwaybetween and not engaging the contact lingers 18 and 18 in the normalrelative positions of the rod 42 and sleeve 82.

When the rod 42 shifts in the left-hand direction relative to the sleevemember 82, the contact finger 8l is bent into contact with the contactfinger 18. When the rod 42 is shifted in the right-hand direction withrespect to the sleeve 82, the inherent bias of contact finger 8l causesit to engage the contact finger 19.-

As will be explained more fully presently, contact linger 8I engages thecontact finger 18 in response to deceleration of the axle II and engagesthe contact finger 19 in response to acceleration of the axle I I.

' The switches formed by the contact fingers 8|, 18, and 19 may beemployed for any desired indicating or control purpose. By way ofexample, I have shown a simple circuit including a source of current inthe form of a storage battery 83 and two signal lamps 84 and 85. Thearrangement is such that when the contact finger 8i engages contactfinger 18, the circuit for the signal lamrp 84 is completed and when thecontact finger 8I engages the contact finger 19 the circuit forthesignal lamp 88 is completed.

Operation When the axle II is not rotating, the rod 42 and the sleeve 82are respectively shifted to their normal positions, in which they areshown, by the springs 45 and 85 respectively. The rod 42 is thus sorelated in position normally with` respect to the sleeve 62 that thecontact finger II is positioned centrally between and out of contactwith the two contact fingers 18 and 19. The circuits for the two signallamps 84 and 8l are correspondingly interrupted.

Upon the rotative acceleration of the axle II, the centrifuge device I8is rotatively driven in response to rotation of the centrifuge device I1by reason of the eddy current clutch formed by the combined inductorring and fly-wheel 48 and the magnetic member 29. As is usual ink thecase of eddy current clutches, with a given load thereon the drivenelement has a certain percentage slip or lag in rotational speed withrespect to the rotational speed of the driving element. The term slipVas used in this connection is distinct in meaning from and is not to beconfused with the term slip as applied to vehicle wheels. Thus, thefly-wheel 48, corresponding to the driven element, has a certain normaland substantially constant percentage slip or lag with respect to therotational speed of the member 29, corresponding to the driving element.The normal per cent slip of the fiy-wheel 48 with respect to axle II isthus substantially constant. Some variation in the slip of the ily-wheelmay occur due to variation of the load on thefly-wheel due to variationof wind resistance with variations in speed but such variation in theslip is not substantial.

The weight of the centrifuge weights 99and 51 and the mannerof mountingthereof is such that the centrifugal forces exerted on the rod 42 andcuit for the signal lamp 85 is thus interrupted and sleeve 82 inopposition to the yielding forces of the springs 45 and Il aresubstantially the same for the same rotational speeds of the twocentrifuge devices I1 and I8. In order, therefore, to cause anequivalent movement of the sleeve 82 in the right-hand directioncorresponding substantially to the movement of the rod 42 when ther axlerotates at a constant speed or accelerates and decelerates at low rates,the spring 85 is designed to have a proportionally lesser pick-up valuethan the spring 48. Thus, notwithstand ing the fact that the centrifugedevice I8 rotates normally at a slower speed than the centrifuge deviceI1, substantially the same movement of the rod 42 and sleeve 82 occursin response to variations in axle speed as long as the normal percentageof slip or difference in speed between the centrifuge device I8 and thecentrifuge device I1 is not too greatly departed from.

As long as the axle II rotatively accelerates at a sufficiently lowrate, the normal percentage slip or lag of the centrifuge device I8 withrespect to the centrifuge member I1 is notgreatly exceeded. Thus, therod` 42 and sleeve 82 remain in their vnormal relative positions duringacceleration at a low rateyso that the switch contact finger 8I remainspositioned between and out of contact with the contact fingers 18 and19.

' If the axle II rotatively accelerates at an abnormally rapid rate,however, the percentage of slip or lag in the rotational speed of thecentrifuge device I8 with respect to the rotational speed of thecentrifuge device I1 increases substantially above the normal value. Insuch case, therefore, the switch operating rod 42 is shifted a greateramount out of its normal position in the righthand direction than is thesleeve member 62 and consequently the contact finger 8| is permitted toengage the contact finger 19 to complete the circuit for the signal lamp85. It will thus be seen that the signal lamp 85 is illuminated onlywhen the axle II rotatively accelerates at a sufciently rapid rate.

When the axle I I ceases to accelerate rotatively and rotates at aconstant speed, the centrifuge device I8 is restored to the normalpercentage slip or lag with respect to the speed of the centrifugedevice I1. The switch rod 42 and sleeve 62 are thus restored to theirnormal relative positions and the contact finger 8l is thus shifted toits normal position centrally between and out of contact with thecontact fingers 18 and 19. The cirthe lamp extinguished.

When the axle I I rotatively decelerates, the centrifuge device I1correspondingly decelerates in speed. At the same time, the combinedinductor ring and fly-wheel 48 andthe centrifuge device I8 rotativelydecelerate due to the braking effect of air friction on the parts of thecentrifuge device and friction in the bearing reces 49 and 5I. Due tothe momentum of the y-wheel 48, however, the centrifuge device I8decelerates at a lesser rate than the centrifuge device I1 and axle I I.Consequently, the percentage slip of centrifuge device I8 with respectto centrifuge device I1 decreases from the normal value.

even accelerate, after remains between and out o! contact with thecontact nngers 1l and 18 as long as the axle Il rotatively deceleratesat a low rate.

If the axle Il and centrifuge device I1 decelerate at a suiiicientlyrapid rate, however, the 5 ily-wheel 48 and centrifuge device I8promptly overspeed, that is, rotate at a speed higher than therotational speed of the axle and centrifuge device I1 because the speedof the axle and centrifuge device I1 reduces so rapidly compared to lothe speed of the ily-wheel 48 and centrifuge device I8. In such case,therefore, since the normal percentage slip of centrifuge device I8 withrespect to centrifuge device l1 is substantially departed from, beingreduced to zero and even to i8 a negative value, the sleeve 82 will becorrespondingly shifted a greater degree in the right-hand directionwith respect to its normal position than the rod 42. The diil'erentdegrees of movement of the rod and sleeve thus causes the rod 42 toengage the Contact finger 8| and bend it in the lefthand direction intocontact with the contact finger 18. The circuit for the signal lamp 84is thus completed and the lamp illuminated only if the axle IIrotatively decelerates at a sufficiently rapid rate.

It will be apparent that when the centrifuge device I8 and fly-wheel 48rotate at a higher speed than the centrifuge device I1 and axle II, thatis, in negative slip relation thereto, the eddy current clutch formed bythe association of the pole-pieces 3| and 32 with the inductor ring andily-wheel 48 is converted into an eddy current brake. In such case,therefore, an eddy current braking effect is exerted on the fiy-wheel 48which is in addition 35 to the braking effect due to the air and bearingfriction.

If the axle Il ceases to decelerate and rotates at a constant speed orbegins to accelerate, the braking eii'ect exerted on the ily-wheel 48and (0 centrifuge device I8 causes the centrifuge device I8 to berestored to a speed having its normal percentage slip relation withrespect to the speed of the centrifuge device I1 and axle Il. In suchcase, therefore, the sleeve i2 and rod 42 are re- 45 stored to theirnormal relative positions in which the contact linger 8l iscorrespondingly restored to its normal position substantially midwaybetween and out of contact with the contact lingers 'I8 and 19. Thecircuit for the signal lamp 84 is thus interrupted and the lampextinguished.

It will be apparent that as long as the centrifuge device I1 and theaxle Il rotate at a Speed such that Substantially less than the normalpercentage slip occurs between the speed of centrifuge device I8 andcentrifuge device I1, the rod 42 will remain shifted in the left-handdirection with respect to the sleeve 82 and the contact nger 8| willthus continue to engage the contact linger 18. Thus, once the contactfinger 8| engages the contact finger 18, in response to deceleration ofthe axle Il, it will remain in engagement with the contact ilnger 18until such time as the two centrifuge devices I1 and I8 are restored totheir normal relative rotational speeds. The axle II may ceasing todecelerate, but the contact finger 8l will still remain in engagementwith the contact linger 18 as long as the normal percentage sliprelation of centrifuge device I 8 with respect to eentrifilge device I1is suillcient to maintain the contact finger 8l in engagement with thecontact finger 18.

Although I have shown my deoelerometer apsignal lamps in Fig. 1, it uparatus as controlling will be seen that the apparatus may be effective,as shown in Fig. 3, to control a suitable magnet valve device 81 whichis in turn elective, when operated, to cause a rapid reduction in thedegree of application of the brakes associated with a vehicle wheelwhenever the vehicle wheel attains an abnormal rate of deceleration suchas occurs only when the wheel slips. In such case, the engagement of thecontact linger 8| with the contact finger 18 will cause completion ofthe energizing circuit for the magnet winding of the magnet valve. 'I'heconsequent operation of the magnet valve instantly initiates a reductionin the pressure of fluid supplied to the brake cylinder 88 and thus acorresponding reduction in the dence of application of the brakes.Thereafter, as the slipping wheel ceases to decelerate and begins toaccelerate back toward a speed corresponding to car speed, the contactlinger 8| is maintained in engagement with the contact finger 18 therebycausing the magnet valve to continue the reduction in the degree ofapplication of the brakes until such time as the slipping wheel isrestored substantially to a speed corresponding to the speed of the car,that is, until such time as .the two centrifuge devices IT and I8 rotateat their normal relative speeds.

My deoelerometer apparatus is so designed and constructed when employedin connection with vehicle brake control systems that the braking effecton the ily-wheel 48 during deceleration oi' the axle II causes thefly-wheel to rotatlvely decelerate at least at a rate which correspondssubstantially to the normal rate of deceleration of the axle II undernon-slipping conditions. It

will thus be seen that restoration oi' the centriiuge device I1 to thenormal rotational speed with respect to the centrifuge device I8corresponds to the restoration of the axle I I to a speed correspondingto car speed.

My decelerometer apparatus is thus adapted not only to operate toinitiate a reduction in the degree of application of the brakesassociated with a wheel substantially at the instant slipping of thewheel begins but is also inherently operative to cause the reduction inthe degree of application of the brakes to continue until such time asthe slipping wheel is restored substantially to car speed, that is,ceases to slip.

My deoelerometer apparatus is similar, in principle, to thedeoelerometer apparatus disclosed and claimed in the copendingapplication Serial No. 460,068 of Clyde C. Farmer, iiled September 29,1942, wherein the structural features are more broadly claimed than inthe present application.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. Acceleration and deceleration responsive apparatus comprising, incombination, a rotary element adapted to be rotated at diil'erentspeeds, a combined inductor ring and ily-wheel member. magnetic meanscarried by said rotary element and associated with said combinedinductor ring and ily-wheel in a manner to induce eddy currents thereinupon rotation of the rotary element whereby said inductor ring andfly-wheel is ro tatively driven at a speed having a certain normalpercentage slip with respect to the rotational rotary element, a firstcentrifuge device rotatable in accordance with the rotational speed ofthe rotary element, a second centrifuge device rotatable in accordancewith the rotational speed of the combined inductor ring and fly-wheel,two cooperating relatively movable asaasvs elements one of which ispositioned in accordance with the rotational speed of the said firstcentrifuge device and the other of which is positioned in accordancewith the rotational speed of the said second centrifuge device,.a firstswitch device operated in response to a predetermined degree of relativemovement of said two elements in one direction, and a second switchdevice operated in response to a predetermined degree of relativemovement of said two elements in the opposite direction.

2. Acceleration and deceleration responsive apparatus comprising, incombination, a rotary element adapted to be rotated at different speeds,a ily-wheel, eddy current clutch means associating the rotary elementand the ily-wheel in a manner to cause the ily-wheel to be rotated at aspeed having a normal relation to the speed of rotation of the rotaryelement and effective to permit the fly-wheel to rotate at a speedhaving an abnormal relation to the rotational speed of the rotaryelement. only when the rotary element rotatively accelerates ordeceleraies at a suillciently rapid rate, a. first centrifuge devicerotatable according to the rotational speed of the rotary element, asecond centrifuge device rotatable according to the rotational speed ofthe fly-wheel, two cooperating coaxially disposed members movableaxially relative to each other, one of said members being variouslypositioned axially inA accordance with the rotational speed of the rstcentrifuge device and the other of said members being variouslypositioned axially in accordance with the 4rotational speed of the saidsecond centrifuge device', and control'means operated according to therelative axial positions of said cooperating members.

3. Acceleration and deceleration responsive apparatus comprising, incombination, a rotary element adapted to be rotated at different speeds,a ily-wheel, eddy current clutch means associating the rotary elementand the fly-wheel in a manner to cause the fly-wheel to be rotated at aspeed having a normal relation to the speed of rotation of the rotaryelement and effective to permit the ily-wheel to rotate at a speedhaving an abnormal relation to the rotational speed of the rotaryelement only when the rotary element rotatively accelerates ordecelerates at a sufilkclently rapid rate. a first centrifuge devicerotatable according to the rotational speed of the rotary element, asecond centrifuge device rotatable according to the rotational speed ofthe vfly-wheel, two cooperating coaxially disposed members movableaxially relative to each other, one of-said members being 'variouslypositioned axially in accordance with the rotational speed of the saidilrst centrifuge device and the other of said members being variouslypositioned axially in accordance with the rotational speed of the saidsecond centrifuge device, and control means operatively responsiveaccording to the relative l axial positions of said cooperating members,said control means having an inactive position as long as the ily-wheelrotates at a speed having normal relation to the rotational speed of therotary element and being operated to an active position as long as thefly-wheel rotates at a speed having an abnormal relation to therotational speed ci the rotary element.

4., Acceleration and deceleration responsive apment, a first centrifugedevice rotatable in accordance with the rotational speed of the rotaryelement, a second centrifuge device rotatable in accordance with therotational speed of the combined inductor ring and ily-wheel, twocooperating coaxially disposed elements axially movable relative to eachother, one of said two elements being variously positioned axially inaccordance with the rotational speed of said first centrifuge device andthe other of said two elements being variously positioned axially inaccordance with the rotational speed of the said second centrifugedevice, and control means operatively responsive according to therelative axial positions of said two cooperating elements.

5. Acceleration and deceleration responsive apparatus comprising, incombination, a rotary element adapted to be rotated at different speeds,a combined inductor ring and fly-wheel member, magnetic means carried bysaid rotary element and associated with said combined inductor ring andy-wheel in a manner to induce eddy currents therein upon rotation of therotary element thereby to cause said inductor ring and fly-wheel to berotatively driven at a speed having a certain normal percentage slipwith respect to the rotational speed of the rotary element, a ilrstcentrifuge device rotatable in accordance with the rotational speed ofthe rotary element, a second centrifuge device rotatable in accordancewith the rotational speed of the combined inductor ring and ily-wheel,two cooperating co-Y

